Synthesis,Characterization and Antimicrobial Activity of Zinc Oxide Nanoparticles against Selected Waterborne Bacterial and Yeast Pathogens

The disinfection of wastewater using nanoparticles (NPs) has become a focal area of research in water treatment. In this study, zinc oxide (ZnO) NPs were synthesized using the microwave heating crystallization technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Qualitative well diffusion and quantitative minimum inhibitory concentration (MIC) tests were conducted to determine the antimicrobial activity of ZnO NPs against selected waterborne pathogenic microbes. FTIR spectral studies confirmed that the binding of urea with Zn occurs through Zn–O stretching. XRD confirmed the crystallized identity in a hexagonal ZnO wurtzite-type structure. The formation of zones of inhibition and low MIC values in the antimicrobial analysis were indicative of the effective antimicrobial activity of zinc oxide nanoparticles against the test microorganisms. The application of metallic nanoparticles in water treatment could curb the spread of waterborne microbial diseases.     

Synthesis of Zinc Oxide Nanoparticles Using Rubus fairholmianus Root Extract and Their Activity against Pathogenic Bacteria

Recently, the biosynthesis of zinc oxide nanoparticles (ZnO NPs) from crude extracts and phytochemicals has attracted much attention. Green synthesis of NPs is cost-effective, eco-friendly, and is a promising alternative for chemical synthesis. This study involves ZnO NPs synthesis using Rubus fairholmianus root extract (RE) as an efficient reducing agent. The UV spectrum of RE-ZnO NPs exhibited a peak at 357 nm due to intrinsic bandgap absorption and an XRD pattern that matches the ZnO crystal structure (JCPDS card no: 36-1451). The average particle size calculated from the Debye–Scherrer equation is 11.34 nm. SEM analysis showed that the RE-ZnO NPs spherical in shape with clusters (1–100 nm). The antibacterial activity of the NPs was tested against Staphylococcus aureus using agar well diffusion, minimum inhibitory concentration, and bacterial growth assay. The R. fairholmianus phytochemicals facilitate the synthesis of stable ZnO NPs and showed antibacterial activity.     

Fabrication and Characterization of Cysteine-Functionalized Zinc Oxide Nanoparticles for Enzyme Immobilization

A green approach is reported for the synthesis of cysteine-functionalized zinc oxide nanoparticles using potato extract as a nontoxic and economical reducing agent. The cysteine-functionalized nanoparticles were used as a support for enzyme immobilization. The structural morphology, crystallinity, and surface functionalization were characterized by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy, respectively. Spherical nanoparticles from 150 to 200?nm were used to evaluate the immobilization efficiency for urease through covalent attachment on the glutaraldehyde-activated amino group of cysteine. In comparison to the unmodified nanoparticles, 62.9% enzyme loading with 72.45% of enzyme specific activity was recovered which was 56% higher than on bare zinc oxide nanoparticles. The point of addition of cysteine during the nanoparticle synthesis had a direct effect on the immobilization efficiency. The immobilized enzyme-specific activity was reduced to 34.32% when cysteine was added following the nanoparticle synthesis. With a facile synthesis procedure and significant immobilization efficiency, cysteine-functionalized zinc oxide nanoparticles were shown to be suitable for various clinical and industrial applications.     

Rubus Capped Zinc Oxide Nanoparticles Induce Apoptosis in MCF-7 Breast Cancer Cells

Rubus fairholmianus (RF) has widely been used to treat various ailments, including pain, diabetes, and cancer. Zinc oxide nanoparticles (ZnO NPs) have drawn attention in modern healthcare applications. Hence, we designed this study to synthesize zinc oxide (ZnO) nanoparticles using R. fairholmianus root extract to investigate its synergistic cytotoxic effect on MCF-7 cells and explore the possible cell death mechanism. ZnO NPs were synthesized via green synthesis using R. fairholmianus root extract, and the effect on MCF-7 cells was determined by looking at cellular morphology, proliferation, cytotoxicity, apoptosis, and reactive oxygen species (ROS). The results showed that cellular proliferation was reduced following treatment with R. fairholmianus capped zinc oxide nanoparticles (RFZnO NPs), while cytotoxicity and ROS were increased. There was also an increase in apoptosis as indicated by the significant increase in cytoplasmic cytochrome c and caspase 3/7 (markers of apoptosis), as well as increased levels of pro-apoptotic proteins (p53, Bax) and decreased levels of anti-apoptotic protein (Bcl-2). In conclusion, these results showed that RFZnO NPs induce apoptosis in breast cancer cells via a mitochondria-mediated caspase-dependent apoptotic pathway and suggest the use of acetone root extract of R. fairholmianus for the treatment of cancer-related ailments.     

沉淀溶解法制备纳米硫化锌

以烷基黄原酸锌和硫化钠分别为锌源和硫源，采用烷基黄原酸锌沉淀溶解法制备了粒度可调、粒径分布比较窄的面心硫化锌纳米粒子，利用比表面积(BET)测定、透射电镜(TEM)、粉末X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)等方法对合成的硫化锌纳米粒子进行了表征。结果表明随着烷基黄原酸锌链长的增长，通过添加硫化钠而生成的硫化锌纳米粒子的粒径逐渐减小。本文还对沉淀溶解法制备纳米硫化锌的溶液化学反应机理进行了探讨。     

Effect of Zinc Oxide on Morphology and Mechanical Properties of Polyoxymethylene/Zinc Oxide Composites

This paper studies the effects of zinc oxide (ZnO) on morphology and mechanical properties of pure polyoxymethylene (POM) and POM/ZnO composites. POM/ZnO composites with varying concentration of ZnO were prepared by melt mixing technique in a twin screw extruder. The dispersion of ZnO particles on POM composites was studied by scanning electron microscope (SEM). It is observed that the dispersion of ZnO particles is relatively good. The mechanical properties of the composites such as tensile strength, stress at break, Young's modulus and impact strength were measured. Increasing content of ZnO up to 4.0 wt% increases the impact strength of POM. Addition of ZnO beyond 4.0 wt% decreases the impact strength. The composites containing ZnO content greater than 2.0 wt% show increased Young's Modulus. The tensile strength and stress at break decrease with increasing ZnO content. This may be due to the compatibility between ZnO and POM.     

单分散性银纳米粒子的可控制备

以卤化银或氧化银作为前驱体,室温下以水为溶剂,在较高溶液浓度下,利用化学还原法制备了单分散性银纳米粒子,并通过改变前驱体的种类,实现了粒径可控制备。采取扫描电子显微镜（SEM）、紫外-可见光谱仪（UV-Vis）、X射线-粉末衍射仪（XRD）、X射线-光电子能谱仪（XPS）等对所制备的银纳米粒子的形貌及成分进行了表征。结果显示,所制备的银纳米粒子具有较高的单分散性,粒径在40~150 nm之间,具有面心立方多晶结构。该方法制备的银纳米粒子可用于喷墨打印RFID天线。     

纳米氧化锌的合成与表征

纳米氧化锌的合成与表征何勇宁，沈孝良，马礼敦（复旦大学分析测试中心上海２００４３３）关键词纳米材料，氧化锌，合成，表征制备纳米材料的方法很多，如蒸发冷凝法、化学气相沉积法、溶胶－凝胶法、超临界法、水热法及各种热分解法等。Ｌｉｕ等［２］用超声雾化热分解...     

Plasma Synthesis of Advanced Metal Oxide Nanoparticles and Their Applications as Transparent Conducting Oxide Thin Films

This article reviews and summarizes work recently performed in this laboratory on the synthesis of advanced transparent conducting oxide nanopowders by the use of plasma. The nanopowders thus synthesized include indium tin oxide (ITO), zinc oxide (ZnO) and tin-doped zinc oxide (TZO), aluminum-doped zinc oxide (AZO), and indium-doped zinc oxide (IZO). These oxides have excellent transparent conducting properties, among other useful characteristics. ZnO and TZO also has photocatalytic properties. The synthesis of these materials started with the selection of the suitable precursors, which were injected into a non-transferred thermal plasma and vaporized followed by vapor-phase reactions to form nanosized oxide particles. The products were analyzed by the use of various advanced instrumental analysis techniques, and their useful properties were tested by different appropriate methods. The thermal plasma process showed a considerable potential as an efficient technique for synthesizing oxide nanopowders. This process is also suitable for large scale production of nano-sized powders owing to the availability of high temperatures for volatilizing reactants rapidly, followed by vapor phase reactions and rapid quenching to yield nano-sized powder.     

氧化铽团簇的表面修饰及对其荧光特性影响的研究

采用脉冲激光轰击浸于流动相中的氧化铽固体靶，考察了流动相及其流速、脉冲激光输出功率、修饰剂、添加修饰剂顺序等对所获得的氧化铽有机溶胶荧光性能的影响。UV-Vis和荧光光谱的测试表明：以含有修饰剂的无水乙醇作为流动相，可得到良好荧光性能的氧化铽乙醇溶胶，而环己酮与醋酸乙酯均不适合作为该体系的流动相;最佳流速为0.15 mL·s^-1；脉冲激光输出功率大有利于其荧光性能；最佳修饰剂为乙酰丙酮(acac)和2，2′-联吡啶(2，2′-bipy)，且应原位修饰。     

Synergistic Effect between Amoxicillin and Zinc Oxide Nanoparticles Reduced by Oak Gall Extract against Helicobacter pylori

Helicobacter pylori (H. pylori) is a global health threat, and the World Health Organization has included H. pylori among 12 bacterial species that require high priority future strategies for the development of new antibiotics due mainly to its high rates of resistance. Metallic nanoparticles are known for their antimicrobial properties. The FDA (Food and Drug Administration) has approved zinc oxide nanoparticles (ZnONPs) as biocompatible antimicrobials. Green synthesis of ZnONPs was performed based on Oak galls extract (OGE) and was characterized by UV, IR, DLS, TEM, and SEM measurements. In addition, LC-MS/MS was used for the identification of OGE constituents. A checkerboard assay was used to evaluate the activity of synthesized Qi-ZnONPs and OGE against H. pylori, and their synergistic effects with amoxicillin were evaluated. LC-MS/MS analyses identified 20 compounds as major gallic acid conjugates. The ZnONPs had average particle sizes of 5.5 nm (DLS) and 7.99 nm (TEM). Both OGE and Qi-ZnONPs exhibited moderate activity against H. pylori. Amoxicillin and Qi-ZnONPs combinations (1:2 and 1:4 amoxicillin:/Qi-ZnONPs) significantly decreased the MIC₉₀ by two-fold and four-fold, respectively, and FIC values for the combinations were more significant than with OGE alone. OGE is rich in phenolics. The synergism between Qi-ZnONPs and amoxicillin can provide an alternative safe agent of low cost to combat H. Pylori infections.     

Synthesis and Optical Properties of Mn2+-Doped ZnS Nanoparticles in Solutions and Coatings

Mn2+-doped ZnS nanoparticles with different Mn-doping concentrations stabilized by hydroxypropyl cellulose (HPC) have been synthesized in ethanolic solutions and coatings. Their optical and structural properties have been characterized by means of UV-vis spectroscopy, luminescence spectroscopy, high resolution transmission electron microscopy (HRTEM) and small angle X-ray scattering (SAXS). Solutions and coatings exhibit a strong luminescence at 590 nm when excited with UV light showing that Mn2+ is incorporated into the ZnS nanoparticles. The highest luminescence intensity is obtained with an Mn2+ concentration of 2 mol%. HRTEM and SAXS investigations show that the particles are crystalline and are 3 ± 0.5 nm in size. Irradiation of the coatings with UV light leads to a photochemical oxidation of the particles, as shown by the decreasing absorption of the coating with irradiation time and a blue shift of the absorption maximum. Furthermore, the luminescence intensity first strongly increases and then decreases completely with UV-irradiation time. Both phenomena can be explained by the photochemical oxidation of the particles.     

Photochemical Synthesis,Spectral-Optical and Electrophysical Properties of Composite Nanoparticles of ZnO/Ag

The photochemical synthesis of nanoparticles of ZnO/Ag in isopropanol solutions has been carried out. Their optical properties have been studied and the parameters of the plasma resonance of the nanoparticles of silver in the ZnO/Ag composites have been calculated. It has been established that the hypsochromic shift of the plasma band of silver observed on irradiation of the nanocomposite is a result of accumulation of excess electrons on the ZnO/Ag particles which leads to equalization of the potentials of the conductions zones of the semiconductor and the metallic components of the nanocomposite.     

花状氧化锌纳米晶的制备及其电化学传感研究

本文以丙三醇为反应溶剂,在氧氧化钾体系中制备了两种花状氧化锌纳米晶.讨论了不同实验条件对氧化锌纳米晶形成影响,通过改变氢氧化钾浓度、反应温度和体系中水含量等条件来调节材料形貌.探讨了花状氧化锌纳米晶可能的形成过程.用X射线粉末衍射、扫描电子显微镜、紫外可见光谱等分析技术对制备的氧化锌纳米晶进行了表征.结果表明两种花状纳...     

Mild Microfluidic Approaches to Oxide Nanoparticles Synthesis

Oxide nanoparticles (oxide NPs) are advanced materials with a wide variety of applications in different fields. The use of continuous flow methods is particularly appealing for their synthesis due to the high control achieved over the reaction conditions and the easy process scalability. The present review focuses on the preparation of oxide NPs using microfluidic setups at low temperature (≤80 °C), since the employment of mild reaction conditions is crucial for developing sustainable and cost-effective processes. A particular emphasis will be put on the improvement over the final product features (e. g., size, shape, and size distribution) given by flow methods with respect to conventional batch procedures. The main issues that arise by treating NPs suspensions in microfluidic systems are product deposition or channel clogging; mitigation strategies to overcome these drawbacks will also be presented and discussed.